GB2181258A - Apparatus for testing welded joints between plastics profiled frame members - Google Patents

Abstract

Apparatus for testing a welded corner joint between two plastics profiled frame members 17, 18 comprises a rigid base 10, an abutment 12, 15 fixed on the base structure and providing a fixed horizontal pivot edge 14, and a clamp 20 for clamping one of the frame members 18 to the rigid base with the frame member extending upwardly across the pivot edge 14 at right angles thereto. The portion of the frame member below the pivot edge 14 is secured against movement by the clamp 20 and the portion above the pivot edge is free to pivot about the pivot edge. An hydraulic jack 25 is mounted on the base 10 for applying an upward load via a beam 43 pivoted at 44, saddle 45 and swivel head 30 to the other horizontal frame member 17 at an adjustable location spaced from the welded joint between the two members and in a direction to cause deflection of the first frame member 18 about the pivot edge 14. A meter 32 is provided for measuring the deflection of the first frame member at a predetermined distance from the pivot edge 14 upon application of the load. <IMAGE>

Description

SPECIFICATION Apparatus for testing welded joints between plastics profiled frame members The invention relates to apparatus fortesting welded joints between plastics profiled frame members, and in particular to apparatusfortesting a welded corner joint between two plastics profiled frame members, such as may be employed in a plastics window frame.

There is increasing manufacture and use of windowframes in which the frame members are extruded profiles of plastics material, usuallywith internal metal reinforcement. At cornerjoints, whether or not the metal reinforcements are also mechanic allyjoined, it is usual forthe plastics frame members to be mitred and secured together by heat welding.

In orderthatsuchwindowframesshould notfail, particularly as a result ofthewelds being stressed due to deformation oftheframe members during in- stallation, it is desirable to ensurethatall such welds conform to a minimum acceptable strength. To this end certain standard testing methods have been proposed. According to one such method a samplejoint between two frame members is tested to destruction by forcing the internal angle between the members over a shaped abutment, or otherwise loading it, until breakage of the joint occurs, the load applied to achieve this being a measure ofthe strength ofthe weld.Such method is undesirable since not only is it destructive of the joint being tested, but in many cases the load required to break the joint is extremely high with the result that testing the equipment must be massive and expensive.

Accordingly, an alternative and preferred standard test comprises securing one frame memberto a fixed support,applyinga loadtotheotherframemember in a direction to tend to open out the joint, and measuring the deflection of one ofthe frame members which results from the applied load. If the joint can withstand a specified deflection withoutfailu re it is deemed to conform to the predetermined standard.

While such a welding quality test is satisfactory in principle, problems arise in applying the test in a con sistentcontrollable manner. For example, it has been suggested that one method of carrying out the test might beto clamp one of the frame membersvertic allyagainsta fixed supportwith the welded joint at its lower end and the other frame member extending horizontally away from the fixed support. A load is then suspended from the horizontal frame member ata specified distance from the weld and the load increased until the frame member reaches a specified deflection at a specified location. Ifthis deflection is reached without breakage ofthe welded joint, it is deemed to be ofthe standard required.

However, to perform the test in this manner is inconvenient and liable to inaccuracies of measurement. There exists, therefore, a need for a testing apparatus which is accurate, consistent, and simple to operate as well as being comparatively inexpensive and it is an object of the present invention to provide such a testing apparatus.

According to the invention there is provided appar atusfortesting a welded corner joint between two plastics profiled frame members, comprising a rigid base structure, an abutment fixed in relation to the base structure and providing a fixed straight pivot edge, means for clamping one of said frame members to said rigid base structure with the frame member extending across said pivot edge at right angles thereto, the portion of the frame member to one side of the pivot edge being secured against movement and the portion on the other side ofthe pivot edge being free to pivot about the pivot edge and being connected by the weld to be tested to the other frame member, load applying meansforapplying a load to said other frame membertransversely to its length at a location spaced from the welded joint between the two members and in a direction to cause deflection ofthe first member about said pivot edge, and means for measuring the deflection ofthefirst member at a predetermined distance from said pivot edge upon application of said load.

Preferably stop means are provided on the rigid base structure for engagement with surfaces of the frame members to facilitate location of the frame members, and the welded joint between them, in a predetermined position on the apparatus.

The aforesaid abutment fixed in relation to the base structure may provide a flat surface against which one portion of said one frame member is clamped by clamping means, the aforesaid pivot edge being an edge of the abutment defining one boundary of said surface.

The meansformeasuring the deflection ofthefirst member at a predetermined distance from the pivot edge may comprise a followerwhich is mounted on a support so as to be displaceable relatively thereto in the direction of deflection, which follower is en gageablewith a surface of said one frame member at a predetermined distance from said pivot edge and is connected to indicating means which indicates displacement of the follower from a datum position. For example, the indicator means may comprise a poin termovableoverascale,such as a dial, the pointer movable over a scale, such as a dial, the pointer being coupled to the follower by an appropriate mechanical transmission.

Preferably the supportfor the follower is displaceable relatively to the rigid base structure, in the direction of displacement of the follower relatively to the support, whereby displacement of the follower beyond a predetermined limit results in displacement of the support relatively to the base structure so asto preventdamageto the indicating means. For example, the supportforthefollower may be pivotably mounted on the fixed base structure, spring means being provided to retain the support in a datum position, but allowing the supportto deflect should the displacement of the follower reach a predetermined limit resulting in the restraint provided by the spring means being overcome.

The means for applying a load to said otherframe membertransversely to its length may comprise a fluid energised piston and cylinder device one part of which, preferably the cylinder, is fixedly mounted on the base structure and the other part of which, preferably the piston, is connected to meansfortrans mitting a load to a part of the otherframe member spaced from the welded joint.

The piston and cylinder device may comprise a manually operable hydraulic jack. Preferably, indicating means are provided to indicate the load applied bythejacktotheframe member. Forexamplean hydraulic pressure gauge may be connectedtothe cylinder ofthe jack.

The following is a more detailed description, by way of example, of apparatus according to the invention, reference being madetotheaccompanying drawings in which: Figure lisa diagrammatic perspective view of the apparatus, seen from the front, and Figure 2 is a rear view of the deflection-indicating means incorporated in the apparatus.

Referring to Figure 1, the testing apparatus comprises a fixed rigid base structure 10 having atop plate 11. Rigidly mounted on the base structure is a vertical abutment block 12 having a flat front face 13 and atop horizontal edge 14which constitutes the aforementioned pivot edge. A support block 15 serves as a buttress supportforthe abutment block 12 and may be integrally formed therewith or may be a separate block welded thereto.

The partframe assembly to be tested is indicated generally at 16 and comprises an upper horizontal frame member 17 of extruded plastics material, and a similar vertical plastics frame member 18, the ends of thetwoframe members being mitred and secured together by a welded join indicated at 19.

The vertical frame member 18 is located with its outer surface flat against the front flat surface 13 of the abutment block 12, and the member is clamped to the abutment block by a clamping screw 20 which passes in threaded engagementthrough a vertical support beam 21 fixedly mounted on the base structure 10. In the arrangement shown only one clam ping screw 20 is shown but it will be appreciated that two or more may be provided.

In orderto locate the assembly 16 in the correct position on the apparatus, i.e. with the lowermost end of the joint 19 a predetermined distance above the pivot edge 14, there is provided a datum support bar 22 mounted on the upper end ofthesupport beam 21. An aperture 24 is provided in the upper plate 11 ofthe base structure to provide clearance for the lowerend ofthe vertical frame member 18.

Spaced horizontally away from the abutment block 12 is an hydraulic manually operable jack 25. The cylinder 26 of the jack extends verticallyfrom a base block 27 which is adjustably mounted on the upper plate 11 ofthe base structure and secured by a releas able clamping device 28. The arrangement is such that the jack may be adjusted towards and awayfrom theabutmentslab l2aswell as laterally.

The upper end of the piston 29 of the jack is con nected by parallel pivotal links 42to a generally hori zontal arm 43. One end of the arm 43 is pivotallycon- nected to the upper end ofthe support beam 21, below the support bar 22, by a horizontal pivot pin 44, so that the arm 43 may swing up and down.

Asaddle member 45 is slideable along the arm 43 and may be clamped thereto by a clamping screw 46.

There is mounted on the saddle member45, by means of a universal swivel, a head 30 which engages the underside of the horizontal frame member 17.The operating handleofthehydraulicjackisindi- cated at31 and an hydraulic pressure gauge 32 is connected tothejack in known mannertoprovidean indication of the vertical load applied by the jack.

It will be appreciated that extension of the jack 25 will apply an upward load to the horizontal frame member 17 and this in turn will cause the upperportion ofthe vertical frame member 18 to bend to the left, about the pivot edge 14, stressing the welded joint 19. The means for indicating the deflection of the frame member 18 at a specified distance above the pivot edge 14 is indicated at 32.

The adjustment ofthe saddle member 45 along the arm 43 enables the load to be applied at any required distance from the weld, whereas the lateral adjustment ofthe jack 25 on the base structure enables the head 30to be located in a position where itfirmly engages an appropriate surface on theframe member, so that assemblies with different profiles may be tested.

The deflection indicating means comprise a support arm 33 which, as best seen in Figure 2, is pivotally mounted at 34 on the support blockl5forthe abutment block 12. The support arm 33 is connected to the block 12, above the pivot 34, by a tension spring 35, and a zero adjustment screw 36 passes throughthe arm 33 and engagesthe rearsurface of the slab 12. A cylindrical collar 37 is provided on an integral extension arm 38 on the upper end ofthe support arm 33 and afollower pin 39 is horizontally slideable within the collar 37 and is located so as to abutthe rear surface 40 ofthe vertical frame member 18.The follower pin 39 is connected, in conventional manner, to a pointer and dial indicator41 which indicates the horizontal displacement ofthe pin 39 from a datum position.

In operation of the apparatus, before any load is applied to the frame member 17 bythe jack 25, the follower pin 39 is engaged with the rear surface 40 of the frame member 18 and the dial 41 is zeroed by adjustment of the screw 36. A vertical load isthen applied to the frame member 17 by operation ofthe jack 25 and the load continues to be applied untilthe deflection ofthe upper end of the vertical frame member 18, as indicated on the dial 41, reaches a predetermined value. If this value is reached without failure of the welded joint 19, the joint is deemed to accord to the predetermined standard.

Should the deflection of the frame member by so great as to reach the limitwhichthe dial 41 can cope with, further displacement ofthefollower pin 39 will result in pivoting of the support arm 33 away from the abutment slab 12, against the action ofthe spring 35, so as to prevent damage to the indicating mechanism.

Since, under such testing, mitred welded joints tend to begin to fail atthe lower end of the joint 19, the indicating device 32 is preferably so disposed as to measure the deflection at the level of the lower mostend ofthejoint. Thus, the follower pin 39 is arranged to engage the rearsurface 40 of the vertical frame member 1 8 at the level oftheuppersurfaceof the datum supportbar22.

Currently, it is considered that a suitable acceptable standard for deflection of the frame member at this location,which is 100 mm above the pivot edge 14, is 5 mm, although it will be appreciated that such standard may be varied.

Claims (13)

1. Appa ratus for testing a welded cornerjoint between two plastics profiled frame members, comprising a rigid base structure, an abutment fixed in relation to the base structure and providing a fixed straight pivot edge, means for clamping one of said frame members to said rigid base structure with the frame member extending across said pivot edge at rightanglesthereto,the portionoftheframe memberto one side of the pivot edge being secured against movement and the portion on the otherside of the pivot edge being free to pivot about the pivot edge and being connected by the weld to be tested to the otherframe member, load applying means for applying a load to said otherframe membertransversely to its length at a location spaced from the welded joint between thetwo members and in a direction to cause deflection of the first member about said pivot edge, and means for measuring the deflec tion of the first member at a predetermined distance from said pivot edge upon application of said load.

2. Apparatus according to Claim 1, wherein stop means are provided on the rigid base structure for engagement with surfaces of the frame members to facilitate location oftheframemembers,andthewelded joint between them, in a predetermined position on the apparatus.

3. Apparatus according to Claim 1 or Claim 2, wherein said abutment fixed in relation to the base structure provides a flat surface against which one portion of said one frame member is clamped by said clamping means, the aforesaid pivot edge being an edge of the abutment defining one boundary of said surface.

4. Apparatus according to any one of Claim 1 to 3, wherein the means for measuring the deflection of the first member at a predetermined distance from the pivot edge comprise a fol I ower which is mounted on a support so asto be displaceable relatively thereto in the direction of deflection, which follower isengageablewith a surfaceofsaid oneframe member at a predetermined distance from said pivot edge and is connected to indicating means which indicates displacement ofthe follower from a datum position.

5. Apparatus according to Claim 4, wherein the indicator means comprise a pointer movable over a scale, the pointer being coupled to the follower by an appropriate mechanical transmission.

6. Apparatus according to Claim 4 or Claim 5, wherein the supportforthe follower is displaceable relatively to the rigid base structure, in the direction of displacement of the follower relatively to the sup- port, whereby displacement of the follower beyond a predetermined limit results in displacementofthe support relatively to the base structure so as to prevent damage to the indicating means.

7. Apparatus according to Claim 6, wherein the supportforthe follower is pivotably mounted on the fixed base structure, spring means being provided to retain the support in a datum position, but allowing the support to deflect should the displacement of the follower reach a predetermined limit resulting in the restraint provided by the spring means being overcome.

8. Apparatus according to any of Claims 1 to 7, wherein said meansforapplying a load to said other frame membertransverselyto its length comprise a fluid energised piston and cylinder device one part of which is fixedly mounted on the base structure and the other part of which is connected to means for transmitting a load to a part ofthe other frame member spaced from the welded joint.

9. Apparatus according to Claim 8, wherein said meansfortransmitting a load to the otherframe member includes an arm pivotally mounted on a fixed part ofthe apparatus, said other part ofthe piston and cylinder device being connected to a part ofthe arm spaced from the pivot, which arem carries a thrust member engageable with a part of said other frame memberfrom the welded joint.

10. Apparatus according to Claim 9, wherein said thrust member is adjustably mounted on said arm so that it may be selectively located in different positions along the length ofthe arm.

11. Apparatus according to any of Claims 8 to 10, wherein said piston and cylinder device comprises a manually operable hydraulicjack.

12. Apparatus according to Claim 11,wherein means are providedto indicatethe load applied by the jacktotheframemember.

13. Apparatus for testing a welded cornerjoint between two plastics profiled frame members, sub- stantially as hereinbefore described with reference to the accompanying drawings.